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Vantage Pro2, Olympic Veteran, Still Unmedaled
We knew it was there! Our Vantage Pro2 always seems to find the best views at the Olympics. But this year, it took the eagle-eye of one of our engineers, Bruce, to spot it. He took the above screen shot (literally! It's a shot of his television screen!) while cheering for the freestyle (aerials) skiers. There it was, keeping tabs on the wind and temps up on the tower! We went right to the source and asked Bill Scott, the manager of the 2010 Winter Games Atmospheric Monitoring Networks, Meteorological Service of Canada, in Richmond, BC about the Vantage Pro2 Bruce spotted. Bill told us they installed weather stations both at the venues and "meteorologically upstream." The Davis station was one of many others from RM Young, YSI, OTT, Texas Instruments, and Vaisala. Those games were clearly the Who's Who of weather sensors (and, of course, athletes!!). Full Moon, Blue Skies, and a Vantage Pro2 Plus...(sigh!)
Shawn T. Sankey, a professional meteorologist who works in aviation meteorology, took this photo of the full moon rising over his Vantage Pro2 Plus in Denver, Colorado. The mile-high station watches the weather at 5,220 (1,591 meters) feet above sea level. We like how Shawn has split his installation so that the solar radiation sensor is at 10 feet (3 meters) above ground level, and the anemometer, with secondary temp/hum sensors, is mounted 20 feet (6 meters) above ground level. He also has a rooftop-mounted anemometer and two soil temperature and moisture sensors, located at 4 and 6 inches deep. Now that's an installation suitable for a pro! Little did Shawn's parents know, when he started forecasting the weather at the age of 11, that he would one day grow up to be a meteorologist. "I am one of the lucky ones to actually make a living while enjoying my hobby," Shawn wrote.
>> Back to Menu 2010: Good Year for Holiday Card Photos
Creature from planet Snowtopia? No, it's a Vantage Vue from Keller Peak, in the San Bernardino National Forest near Arrowbear Lake, California. It belongs to Dennis Hughes, who tells us it is located about 8,000 feet (2,438 meters) up the mountain. "Our Skywarn folks monitor our data and pass it to the NOOAA weather service in San Diego," says Dennis.
Tarmo Soodla, of Tallinn, Estonia, learned his manners well. He sent us a nice thank you note, just because. (Because we made him a terrific weather station, that is.) He included this pretty picture of said Vantage Pro2 doing its thing in snowy Tallinn. That pompodor hairdo looks good on you, Vantage Pro2! Palun, Tarmo.
>> Back to Menu Who Cares About Dew Point? We're going to assume we all understand what relative humidity is. (Quick! It's a ratio of the amount of water vapor in the air relative to how much the air, at a specific temperature and pressure, can hold before it is saturated.) Dew point, on the other hand, is a temperature. It is the temperature to which the air must cool in order to be saturated. At this temperature, the moisture in the air begins to condense into clouds or dew. Dew point can tell you the actual amount of moisture in the air, so it is really a better measure of how humid it is, especially in terms of human comfort! (At a given barometric pressure, independent of temperature, dew point indicates the mole fraction of water vapor in the air and therefore its specific humidity. At a given temperature, independent of barometric pressure, dew point indicates absolute humidity.) For example, you might be feeling very muggy and moist on a warm day, only to find a rather disappointingly low relative humidity reading on your console. But then you press 2nd and DEW, and are not suprised to find that the dew point is high. We human types are most comfortable when the dew point is between 50 and 59°F (10 - 16°C). But dew point is useful in ways other than figuring out why we feel so damp and sweaty -- or not! You can also use afternoon dew point to predict the lowest air temperature overnight. Provided no new fronts are expected overnight and the afternoon relative humidity is greater than or equal to 50%, the afternoon's dew point gives you an idea of what minimum temperature to expect overnight. The reason for this is interesting, and a little complicated. We included more information on this topic when we discussed dew point in our May 2008 issue. In cold weather, dew point can also be called the frost point. That's a fact growers and pilots really need to know! Dew point is important in HVAC engineering, and for any engineer concerned with heat transfer, combustion, or energy use. People concerned with storing anything from high tech equipment to paper records want to know the dew point. It is vital for determining evapotranspiration. It is even an important factor in predicting the corrosion of metals. Pilots and sky watchers can use it to determine the altitude of the cloud base. [Cloud Base Altitude = (((temperature in F- dew point in F) / 4.5) x 1000) + measuring station altitude]. This is because rising air masses cool as they rise, and this cooling is a rather constant 5.5°F per thousand feet. With that, the dew point decreases at about 1.0°F over the same distance - for a steady decrease in the spread between air temperature and dew point of 4.5°F/1000 feet. (But don't do the math, grab your console and use the handy calculator on CSGNetwork!) Mapping of dew points is a useful tool in predicting cloud formation over large areas - clouds form where there is dew point depression, and therefore, moist air. So stop ignoring that little DEW button!
>> Back to Menu Will a Heated Rain Collector Provide Snow Depth? Dan Wnenta, of Huntington, New York, asked a very good question. We thought we'd share our Tech Gurus' answer. "We don’t get much snow on Long Island," wrote Dan, "but when we do, I stick a ruler in the snow around my yard and take an average depth. If my Davis Vantage Pro2 rain gauge was heated, would I be able to calculate the snowfall?" Don't throw away your ruler just yet, Dan. The problem with snow is that is has no sense of conformity -- at least as far as water composition. If you heated your rain gauge, you could determine how much moisture the snow contained, but that would not give you any idea of how many inches has fallen. It could be a very wet one inch or a very dry three inches! The Rain Collector Heater does keep your rain collector from becoming a solidly-packed, snow-storage unit.
>> Back to Menu Hardy New Weather Station in Hardy, Arkansas Here's a link to a story from KAIT-8, Jonesboro, Arkansas, about the ribbon cutting ceremony in Hardy, Arkansas, for the town's new weather station, a gorgeous Vantage Pro2. The mayor hopes the station will increase tourism, because visitors can know "what we have to offer and they're going to be able to see it live 24/7 now." Of course, it will also help the Region 8 StormTEAM keep residents informed about the weather. >> Back to Menu Do You Tweet? F to C and Back Again: We Like Your Answers Better Bob Turner, of Woodland, California, wrote: "You asked for a quick way to convert Fahrenheit to Celsius. I've used the following method to convert Celsius to Fahrenheit when I was working at geothermal wells with only a Celsius thermometer: Double the Celsius reading, subtract 10 percent, and then add 32. Example: 35 Celsius would be 35+35=70-7=63+32=95 Fahrenheit. Simple mental math that gives an approximate result. To convert Fahrenheit to Celsius: 95-32=63+6=69/2= about 35." Roman Pennington, of Stockport, Ohio offered this: "Use a calculator. I remember way back to the days before calculators when we all used slide rules. I always had a hard time remembering the two different equations. One day I found a very simple equation in a Dodge Engineering Catalog (not the auto company). It is C/100 = (F-32)/180. If you know basic algebra you can solve for either C or F. And if I forget this equation, I reason it out. In the numerator, at freezing C = F-32. In the denominators, there is 100 degrees between freezing and boiling on the Centigrade scale and 180 degrees between freezing and boiling on the Fahrenheit scale. I've used this method for the past 25 years."
Joyce H., of Hayward, CA offered this bit of modern wisdom: "Get an iPhone app!" Ric Has a Better Answer to a Better Rain Question "I was disappointed," Ric wrote, "in both the question and answer to: 'A Good Rainy Day Question: Why is rainfall measured in a length measurement (i.e. mm, inches) rather than a volume measure (mm per sq meter, etc.)?'" Here's Ric's much better answer: "First, mm per sq meter is not volume, it is length divided by length squared, i.e. 1/length. That is not a very useful unit of measurement when looking at rainfall. "Rainfall actually is reported as a volume of rain that falls over some area, i.e. length cubed divided by length squared, and that leaves you with just length, a length we usually refer to as depth. This makes a lot more sense with snow - a regional 10 cm snowfall means 10 cm everywhere, drifting excluded. "So, if you have a 5 mm rainfall, you could have had 5 liters over a square meter. (A liter is 1/1000 of a m3, so 1 liter only covers a m2 to a depth of 1/1000 of a meter, or 1 mm.) That 5 mm of rain over a hectare (10000 m2) would be 50000 liters or 50 m3. Reporting depth makes a lot more sense than reporting volume. "Rainfall expressed as volume is most useful when considered over a watershed because that is useful in looking at river flooding. Knowing the volume is one step in determining the river flow (volume per time, e.g. m3/second) needed to drain the excess rainfall. "The tipping bucket in the Davis ISS tips once for every 0.01" of rain. I think the funnel diameter is 4", so the area (pi x r2) is about 30 in2, so the volume is 0.3 in3. The tipping mechanism measures volume, the console reports the equivalent depth of rainfall." Ric thinks we did better on the question about Barrow, Alaska as an Urban Heat Island (UHI). He wrote, "This is very useful information. Some people are interested in how the UHI effect is falsely suggesting global warming and there is a significant debate about how big an urban area is necessary to produce significant warming. A worrisome number of weather stations now being used to track global warming are located in urban areas and produce very confusing and misleading data. We need a lot more measurements in stable rural areas, and the new US Climate Reference Network is a good step in that direction."
>> Back to Menu What do you think of the E-Newsletter?How can we improve? How do you use your Davis weather products? Email us at news@davisnet.com. Question 1: Where did the term Meteorology come from? In 350 BC, Aristotle published his Meteorologica. While weather was definitely covered, so was just about everything else in what we would call Earth Sciences, from geology to hydrology to the moon and stars. There's a translation on The Internet Classic Archive, if you want to read it for yourself. (It is interesting to note that Aristotle knew the earth was a sphere!) >> Back to Menu Question 2: Which city has the "Snowiest Metropolis" trophy in their showcase? Well, none really, because we don't think there actually is such a trophy. But Sapporo, Japan ought to have it. On the island of Hokkaido, it has an annual snowfall of 248 inches (630 cm). This fact is from our new favorite book: the beautiful Encyclopedia of Weather and Climate Change: A Complete Visual Guide, from The University of California Press. Your coffee table needs a copy! >> Back to Menu Question 3: Does dew fall from the sky? Unlike rain, dew does not fall from the sky. It condenses from the air surrounding the bedewed surface. Extra Credit: Is the dew point inside the house the same as outside? Yes, unless you have humidified the inside air by boiling vats of water or taking hot showers, or dehumidified it by running the air conditioner. The barometric pressure inside the house is the same as outside (which is why our barometers are located in the console, not the ISS). The air temperature is probably different, and the relative humidity will change with temperature, but the dew point will be the same. Since we do tend to take showers and run air conditioners, in reality, they probably are different. So you are right whether you said yes or no! That's the kind of question we like! >> Back to Menu Question 4: Would melted sea ice be good drinking water? Not unless it is old sea ice, or multiyear ice. The salt is pushed out of the crystals, but it gets trapped in pockets between them as brine. Melted new sea ice would be too salty to drink. But if the ice remains for a long enough time, the brine will eventually drain through the ice, leaving ice that could be used for drinking. Extra Credit: If you ordered two Growlers and a Bergy Bit, what would you get? Not two cheeseburgers and a beer! In the categorization of icebergs, it's all about size. The smallest are called Growlers. They are less than 3 feet (1 meter) high and 16 feet, (5 meters) long. The next size up, but not yet Small, are Bergy Bits which are 3-13 feet (1-4 meters) by 15-46 feet (5-14 meters). Bon appetit! (Want to see something very cool and also cold? Click here and scroll down to see a time-lapse video of ice forming on the Baltic Sea.) >> Back to Menu Question 5: To what spot on earth has the high wind gust torch been passed? Barrow Island, Australia. The World Meteorological Association, Note 58 starts out like this: "Geneva, 22 January 2010 (WMO) - According to a recent review conducted by a panel of experts in charge of global weather and climate extremes within the WMO Commission for Climatology (CCl) the record of wind gusts not related to tornados registered to date is 408 km/h during Tropical Cyclone Olivia on 10 April 1996 at Barrow Island, Australia. The previous record was of 372 km/h, registered in April 1934 across the summit of Mount Washington, USA." Thanks to Ric Werme for bringing this to our attention. (And possibly to the attention of Mt. Washington!) >> Back to Menu Davis! What do you think of our new E-news format? Please continue to send your comments, weather URL's, and story suggestions to news@davisnet.com. We look forward to getting your comments and any responses you have to the Davis E-News. Member participation is what keeps the Davis E-News alive and kicking. Well, that's it for this edition. You'll be hearing from us again next month! The Davis Weather Club E-Newsletter is published by Davis Instruments. Vantage Vue, Vantage Pro2, Vantage Pro2 Plus, Vantage Pro, Vantage Pro Plus, Weather Monitor, Weather Wizard, WeatherLink, WeatherLinkIP, Weather Envoy, and Perception are trademarks of Davis Instruments Corp. |
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WEATHER IN ACTION
